1. Technical Field
The present disclosure relates to an expandable sealing mechanism, and associated method, for sealingly compressing a gasket or seal against an annular wall of a rigid structure. More particularly, the present disclosure relates to sealing structures and arrangements for sealingly connecting an opening in a manhole wall to a pipe entering or exiting the manhole wall through the opening.
2. Description of the Related Art
In underground pipe systems, it is often necessary to connect a pipe in a sealed manner within an opening in the wall of a rigid structure, such as a manhole wall. Typically, a flexible elastomeric seal or gasket is placed within the opening in the wall, followed by fitting an expansion ring against the interior surface of the gasket. Thereafter, a suitable expansion mechanism is used to radially expand the expansion ring and lock same in an expanded condition in which the gasket is sealingly compressed between the expansion ring and the opening in the wall of the structure. A pipe is inserted through the gasket, and one or more external clamps are installed around a portion of the gasket which extends from the wall to sealingly compress the extending portion of the gasket between the clamps and the outer surface of the pipe. In this manner, a sealed connection is made between the pipe and the structure.
An alternative application for a sealing device including a gasket/expansion ring combination is underground pipes which are used in municipal water and sewer systems, for example. Such underground pipes typically include bell and spigot ends that are attached to one another in a sealed manner. Typically, either the spigot end or the bell end of such pipes includes a rubber seal which is compressed between the ends of the pipes to provide a sealed joint when the spigot end of one pipe is inserted into the bell end of another pipe. Occasionally, these primary joint seals between adjacent pipes may leak after installation in the field, requiring a secondary sealing assembly to seal the connection.
Yet another application for sealing devices is in the upper openings of manhole systems, which typically facilitate access to the underground pipes from street level. For example, the manhole chimney and riser structure may have seams through which ground water or other surrounding fluids can seep. In some cases, it is desirable to prevent the ingress of these ambient fluids through these seams in the manhole chimney.
One known sealing mechanism includes an expansion ring having a ratcheting engagement between overlapping ends of the ring. When the ends of the ring are forced in opposite directions from one another as the ring is radially expanded, ratchet teeth on the ring ends sequentially engage one another, wherein the expansion ring may be sequentially expanded in an incremental manner into multiple locked positions. A separate tool is used to engage the opposite ends of the expansion ring and to drive same apart from one another.
What is needed is an improved sealing assembly that can be installed within an annular opening, such as an opening in the wall of a manhole, to provide a reliable seal.